Flushing mechanism for a dual flush cistern

ABSTRACT

A flushing mechanism for a dual flush cistern system comprises a float assembly ( 1 ) comprising a hollow valve stem ( 2 ) carrying a sealing valve ( 3 ) for sealing the outlet opening of the cistern at or towards one end and being open at each end to define an overflow passage and a float ( 6 ) fixedly attached around the valve stem ( 2 ), a cylindrical guide member ( 7 ) surrounding the float ( 6 ) and having at the end adjacent the sealing valve at least one opening to allow liquid to pass to the outlet opening, an operating rod ( 17 ) arranged to move vertically upward to raise the float assembly ( 1 ) to open the vavle ( 3 ), first and second operating means ( 25, 26 ) arranged to effect such vertical movement of the operating rod ( 17 ), the first operating means ( 25 ), an operation, being arranged to raise the float assembly ( 1 ) a first distance to a level which the float assembly ( 1 ) is buoyant, and the second operating means ( 26 ) being arranged to raise the float assembly ( 1 ) a second distance, less than the first distance in a level at which the float assembly ( 1 ) is not buoyant, whereby when the first operating means ( 25 ) is operated and released, a first predetermined quantity of liquid flows from the cistern, and when the second operating means ( 26 ) is operated and released a second, smaller, predetermined quantity of liquid flows from the cistern.

BACKGROUND TO THE INVENTION

[0001] In recent years it has, in many countries, been a requirementthat all new toilet cisterns installed should have a dual-flushfunction, in which a full flush releasing a large quantity of flushingliquid can be used when solid waste is to disposed of and a partialflush releasing a smaller quantity of flushing liquid can be used when afull flush is not required, for example, when liquid waste is to bedisposed of.

[0002] Many such mechanisms for dual flush cisterns have been proposed.

[0003] In certain systems the cistern is divided into two parts by aweir having a movable gate such that when a partial flush is requiredthe gate remains closed and only the liquid on one side of the weir isreleased through the cistern outlet but when a full flush is requiredthe gate is opened allowing liquid on both sides of the weir to passthrough the outlet. Examples of such dual flush mechanisms are disclosedin AU-B-56165/80 and WO93/15284.

[0004] Another type of dual flushing mechanism relies on closing theoutlet valve after different times depending on whether a full orpartial flush is required.

[0005] Examples of such mechanism are described, for example, inAU-A-28538/84, AU-B-80111/87, AU-B-40396/85 and WO93/15284.

[0006] The prior art mechanisms generally include a float assemblycomprising a float associated with the valve stem of the outlet closurevalve and either attached to or slideable on the valve stem. The floatreduces the negative buoyancy of the float assembly so that the floatassembly sinks at a slower rate to close the valve than it would do ifthe float were not present.

[0007] The majority of the prior art mechanisms include a large numberof moving parts and are complicated in their structure in that variousnon-linear motions are involved in operation of the valve.

[0008] It is the object of this invention to provide a flushingmechanism for a dual flush cistern that is very much simpler than theexisting mechanisms.

SUMMARY OF THE INVENTION

[0009] This invention provides a dual flush system comprising a floatassembly comprising a hollow valve stem carrying a sealing valve forsealing the outlet opening of the cistern at or towards one end andbeing open at each end to define an overflow passage and a float fixedlyattached around the valve stem, a cylindrical guide member surroundingthe float and having at the end adjacent the sealing valve at least oneopening to allow liquid to pass to the outlet opening, an operating rodarranged to move vertically upward to raise the float assembly to openthe valve, first and second operating means arranged to effect suchvertical movement of the operating rod, the first operating means, onoperation, being arranged to raise the float assembly a first distance,and the second operating means being arranged to raise the floatassembly a second distance less than the first distance, whereby whenthe first operating means is operated and released, a firstpredetermined quantity of liquid flows from the cistern, and when thesecond operating means is operated and released a second, smaller,predetermined quantity of liquid flow from the cistern.

[0010] The float preferably comprises an inverted cup-shaped memberwhich traps air, thereby reducing the negative buoyancy of the floatassembly. The rate of closing the valve is dependent on the hydrostaticpressure acting on the float and on the distance that the float has tomove to close the valve. Thus, the float assembly is designed so thatwhen the float assembly is raised by the first, full flushing, distancethe float is buoyant and so falls to close the valve as the level of theliquid supporting it drops thereby allowing the predetermined quantityof liquid to flow from the cistern. However, when it is raised by thesecond, partial flushing, distance the hydrostatic pressure on the floatsurface is such that the float is not buoyant and the valve starts toclose as soon as the operating means is released the rate of closurebeing such that the second predetermined amount of liquid flows from thecistern.

[0011] In some instances for example when the operating means is helddown for too long a time or is operated too violently the water level inthe cistern may drop so far or the float assembly may gain sufficientmomentum to move further upward than the second predetermined distancethat the assembly may become buoyant. Preferably, therefore, the secondoperating means, on operation, in addition to raising the float assemblyalso operates a stop mechanism acting on some part of the float assemblyto prevent movement of the float assembly greater than the seconddistance in its simplest form, such stop mechanism comprises a rod whichon operation of the second operating means, is introduced into the floatguide member to a predetermined level to contact the upper surface ofthe float when the float has reached the desired height. Preferably, thestop mechanism is adjustable to allow fine-tuning of the quantity ofliquid that flows from the cistern in a partial flush. This may beachieved by means of a screw thread on the road by means of which thelower end of the rod can be raised or lowered relative to the float. Therod preferably passes through a guide member mounted on the rim of thefloat guide member in order to constrain movement of the rod only to anup and down movement.

[0012] The operating means preferably comprises a pair of push buttonson the top of the tank, depression of which moves a pivoted fever whichis connected to the operating rod. However, especially when themechanism is intended for use as a conversion kit for an existing leveroperated cistern the operating means may comprise a pair of levers, forexample mounted on concentric shafts with appropriate linkages to theoperating rod.

[0013] The operating mechanism is preferably carried on a bracket whichis mounted on the side of the float guide means, the length of which ispreferably adjustable to allow the mechanism to be used in cisterns ofdifferent height. In a mechanism in which the length of the bracket isadjustable the length of the operating rod end of the stop rod, whenpresent must also be adjustable.

[0014] In a preferred form of the operating mechanism, the connectionbetween the operating means and the float assembly, comprises a rod orbar with a plurality of spaced holes at least at its end adjacent to thefloat assembly which cooperates with a bracket on the float guide memberwhich also has at least one hole through which a fixing pin can bepassed into one of the holes on the bracket. The operating rod and thestop rod may be telescopic and maybe held together by locating pinswhich can pass through locating holes, as necessary. In the case of thestop rod, the rod is preferably mounted in a U-shaped rod carrier andthe locating pins are permanently attached to the rod sot that the rodcan be rotated to snap the pin into and out of one of a plurality ofnotches on the rod carrier. The rod carrier may be mounted by a screwthread on the second operating means to allow fine adjustment of theeffective length of the rod.

DESCRIPTION OF PREFERRED EMBODIMENT

[0015] The invention will now be described in greater detail by way ofexample with reference to the drawings, in which:

[0016]FIG. 1 is an isometric view of one form of flushing mechanismaccording to the invention in the closed position of the valve;

[0017]FIG. 2 is an isometric view of the valve mechanism of FIG. 1 inthe full flush position;

[0018]FIG. 3 is an isometric view of the mechanism of FIG. 1 in thepartial flush position;

[0019]FIG. 4 is a section through the mechanism of FIG. 1 in the fullflush position but with the stop rod not shown; and

[0020]FIG. 5 is a view as in FIG. 4 in the partial flush position.

[0021] As shown in the drawings, the flushing mechanism comprises afloat assembly indicated generally by reference numeral 1 when comprisesa valve stem 2 which is hollow and open at both ends and carries towardsone end a valve closure member 3 which seats on a valve seat 4 on afixture member 3 by which the float assembly 1 is mounted to the outlet1 (not shown) of a toilet system (also not shown). Float assembly 1 alsoincludes a float 6 in the form of an inverted cup member which isfixedly attached around valve stem 2. Float 6 is closely surrounded by acylindrical portion 7 of a float guide 8. Cylindrical portion 7 isspaced from the bottom of the cistern and the valve seat by means oflegs 9 on a spacer member 10 which is attached to cylindrical portion 7by a bayonet fixing 11 at one end and at the other end is attached tofixture member 5. The base of cylindrical portion 7 is closed to limitthe maximum movement of float assembly 1.

[0022] On its outer surface, cylindrical portion 7 carries a bracket 12for mounting a support arm 13 for the flush operating mechanism. Thesupport arm 13 is cranked at its upper end 14 and terminates in a yoke15 supporting a pivotally mounted operating lever 16. One end of lever16 is attached to a cranked operating rod 17 which extends intocylindrical portion 7 the portion within cylindrical portion 7 beingattached to valve stem 2 by means of a collar 18 which abuts against theunderside of a flange 19 on valve stem 2. Collar 18 is attached tooperating rod 15 by means of a pin 20 which passes into one of a numberof holes 21 in operating rod 17. Downward pressure on the end of lever16 remote from the connection of operating rod 17 causes operating rod17 to move upwardly carrying the float assembly 1 with it and therebycausing the valve 3, 4 to open to allow liquid to exit the cistern.

[0023] Support arm 13 is connected to bracket 12 by means of lockingpins (not shown) engaging in one or more of holes 22 in supporting arm13 so that the distance between the operating mechanism and the floatassembly 1 can be varied to suit cisterns of different height. Operatingrod 17 is formed in two parts, connected by means of pins 23 locating inholes 24 in the two parts of the operating rod 17 thereby allowinglength adjustment of operating rod 17.

[0024] The operating mechanism includes two push buttons 25, 26 whichserve to depress the end of lever 16 remote from the connection ofoperating rod 17.

[0025] The push buttons 25, 26, are spring loaded sot that they arebiased to an inoperative position.

[0026] Each of push buttons 25, 26 has a projection 27, 28 on its lowersurface which, when a button 25, 26 is pressed acts on lever 16 to moveoperating rod 17 upwardly. Projection 27 on the full flush button 26 islonger than the projection 28 on partial flush button 26, so that whenpush button 25 is pressed, the operating rod 17 is lifted by a greaterdistance and hence lifts the float assembly further away from the valveseat 6 then when push button 26 is pressed.

[0027] The projection 28 on push button 26 is connected to a furtherlever 29 which at one end 30 overlaps the operative end of lever 16 andat the other end 31 is attached to a stop rod 32 via a U-shaped rodcarrier 33. Stop rod 32 passes through a guide 34 on the rim ofcylindrical portion 7. Depression of button 26 causes projection 28, inaddition to causing operating rod 16 to move upwardly thereby raisingthe float assembly 1 also depresses stop rod 33 within cylindricalportion 7 to further limit the possible movement of float assembly 1.

[0028] Rod carrier 31 is attached to lever 29 by means of a screw 34which passes through a screw-threaded bore in end 31 of lever 29 toallow adjustment of the distance between rod carrier 33 and lever 29thereby allowing fine tuning of the distance that rod 32 extends intocylindrical portion 7. In addition carrier member 33 has a plurality ofnotches 35 into which a pin 36 protruding from the surface of rod 32 canbe snapped, to allow larger adjustment of the effective length of rod31.

[0029] As shown in FIG. 4, in the full flush position, float assembly 1is raised by means of operating rod 17 to a level such that the top offloat 5 almost reaches the upper edge of cylindrical portion 7. At thislevel the air trapped under float 5 is sufficient to make float assembly1 buoyant so that the float assembly 1 does not sink under its ownweight when push button 25 is released but instead merely falls as thewater level in the cistern drops.

[0030] As shown in FIG. 5, in the partial flush portion, float assembly1 is raised to a lesser level. At this lower level the hydrostaticpressure acting on float 6 is sufficient to overcome the buoyancy offloat assembly 1 so that when push button 26 is released, the floatassembly 1 will sink under its own weight albeit at a slower rate thanit would if the float 6 were not present.

1. A flushing mechanism for a dual flush cistern system comprising afloat assembly (1) comprising a hollow valve stem (2) carrying a sealingvalve (3) for sealing the outlet opening of the cistern at or towardsone end and being open at each end to define an overflow passage and afloat (6) fixedly attached around the valve stem (2), a cylindricalguide member (7) surrounding the float (6) and having at the endadjacent the sealing valve at least one opening to allow liquid to passto the outlet opening, an operating rod (17) arranged to move verticallyupward to raise the float assembly (1) to open the valve (3), first andsecond operating means (25, 26) arranged to effect such verticalmovement of the operating rod (17), the first operating means (25) onoperation, being arranged to raise the float assembly (1) a firstdistance to a level which the float assembly (1) is buoyant and thesecond operating means (26) being arranged to raise the float assembly(1) a second distance, less than the first distance to a level at whichthe float assembly (1) in not buoyant, whereby when the first operatingmeans (25) is operated and released, a first predetermined quantity ofliquid flows from the cistern, and when the second operating means (26)is operated and released a second, smaller, predetermined quantity ofliquid flows from the cistern.
 2. A mechanism according to claim 1,wherein the float (6) comprises an inverted cup-shaped member whichtraps air, thereby reducing the negative buoyancy of the float assembly(1).
 3. A mechanism according to claim 1 or claim 2, wherein the secondoperating means (25), on operation, in addition to raising the floatassembly (1) also operates a stop mechanism (32, 33) acting on some partof the float assembly (1) to prevent movement of the float assembly (1)greater than the second distance.
 4. A mechanism according to claim 3,wherein the stop mechanism (32, 33) comprises a rod (32) which, onoperation of the second operating means (26), is introduced into thefloat guide member (7) to a predetermined level to contact the uppersurface of the float (6) when the float (6) has reached the desiredheight.
 5. A mechanism according to claim 4, wherein the stop mechanism(32, 33) is adjustable to allow fine-tuning of the quantity of liquidthat flows from the cistern in a partial flush.
 6. A mechanism accordingto claim 4 or claim 5 wherein the rod (32) passes through a guide member(34) mounted on the rim of the float guide member (7) to constrainmovement of the road (32) only to an up and down movement.
 7. Amechanism according to anyone of claims 1 to 6, wherein the operatingmeans (25, 26) comprises a pair of push buttons on the top of thecistern, depression of which moves a pivoted lever (16) which isconnected to the operating rod (17).
 8. A mechanism according to anyoneof claims 1 to 7, wherein the operating mechanism is carried on abracket (13) which is mounted on the side of the float guide means (7),the length of the bracket 13 being adjustable to allow the mechanism tobe used in cisterns of different height, the length of the operating rod(17) and of the stop rod (32, 33), when present being also adjustable.